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Installing New Steam Radiator

mculik5 Member Posts: 30
I'm renovating two bedrooms in my house and am installing two new steam radiators as part of the renovation. The radiators are freestanding, cast iron radiators made by Governale. The system is single-pipe.

The radiators have 1 1/4" NPT openings at the bottom (for the valve at one end and plug at the other) and 1" NPT openings at the top. Additionally, about 1/3 of the way up each end section, as well as next to the top 1" NPT opening, there are two small bungs.

Looking at the other radiators in my house, the vents (which are 1/8" NPT) are all installed in the bung that is 1/3 of the way up the end section.

My plumbing supply company said that the vents should be installed using a 1" NPT - 1/8" NPT reducer at the top of the radiator so that the whole thing gets hot. However, I've never had an issue with my other radiators getting completely hot, and don't like the way the vents will look if installed at the top (I'm installing Macon single-pipe thermostatic radiator vents).

Two questions:

1. Should the vents be installed at the top, or is it OK to install them using the bung 1/3 of the way up the end section?

2. Are those bungs meant to be drilled/tapped, and if so, is it standard practice to do that in the field (vs. ordering them pre-tapped)?

Appreciate the help.


  • Steamhead
    Steamhead Member Posts: 16,832
    That guy is wrong

    he must have thought you have a hot-water system. Steam is lighter than air. The vent on a steam rad goes in the lower 1/8" bung, which you will have to drill and tap to 1/8" pipe thread if it's not already done.  
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
  • mculik5
    mculik5 Member Posts: 30

    Thanks for the quick reply.

    I figured he was wrong, since my radiators have been working well since 1939 with the vents installed lower on each end section. Just got concerned/confused when the radiators didn't come pre-tapped for vents.

    How hard is it to drill/tap cast iron? I don't have a drill press or much tapping experience. Better to take them to a machine shop?

    Also, any recommendations on thread sealants for my install? The old (original) radiators were a huge pain to remove because the fittings were rusted together. I'd like to use some kind of thread sealant that will do a good job, but also allow easy removal in the event I (or the next homeowner) want to paint behind the radiators, etc.

    Really appreciate the help.
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    Removing old radiators

    Most radiators are connected using rust-free brass components (spud-valve), so the part to remove should be easy with the right tools and a bit of experience. The union of spud, and valve should only require a little dish washing soap on the mating faces, after a thorough cleaning. For the threads of the riser and valve, use Teflon tape. Remember that the valve and spud are a matching pair, and so a new valve and spud may be necessary.

    Post a picture of the bung, as it may be a pipe-plug, which may unscrew.--NBC
  • VA_Bear
    VA_Bear Member Posts: 50
    Tapping Cast Iron

    Fine grain cast is fairly easy to drill and tap; use a sharp tool steel drill of the correct size for the tap, center tap the entry point, use low drill speeds to prevent overheating and tear out and make sure you use the correct tapping lubricant for both the drilling and the tapping of the hole. Take your time and let the tools do the work.
  • mculik5
    mculik5 Member Posts: 30
    Thanks Again

    This forum is amazing. Thanks for the replies.

    Quick background:

    I'm a first-time homeowner in Northern NJ. I'm a fairly competent DIYer, but heating/plumbing is probably my weakest DIY area, and this is my first experience with steam heat.

    All components from the risers forward are new (risers, valves/spuds, radiators, vents, etc.). My original plan was to replace only the valves and vents. I was going to have the radiators sand blasted/powder coated and reuse them. However, the quote I received for sand blasting/powder coating was very high because of the amount of prep/paint removal required. I did some research, and learned that I could get new radiators and have them powder coated for only a bit more than the original quote. The decision was finalized when I sheared off the tabs inside the spuds trying to get them out.

    Based on the replies, my plan of attack for thread sealing is:

    - Teflon tape on all threads going into radiator (spud, plugs, vent, etc.)

    - Nothing on the nut that pulls the spud/radiator and valve together

    - Teflon tape on both ends of the riser

    I like the "cleanliness" of Teflon tape, so don't want to use pipe dope if I don't have to. I temporarily installed the valves earlier today with only Teflon tape so I could turn the heat on in the rest of the house for my wife, and didn't notice any leaks, so I think I'll be fine without pipe dope.

    Pictures of the bungs are attached. Bungs on one end look like they are plugged, like Nicholas said. I scraped some of the primer off, and the plugs appears to be cast iron, too, and didn't move at all. If they can be unscrewed, please explain how, as they don't appear to have any kind of tool head.

    Again, appreciate all replies.
  • BobC
    BobC Member Posts: 5,477
    treflon tape

    Most teflon tape is very thin but they do make some that is heavier  (3-4 mils, oatey is one name) and makes a better seal than the flimsy tapes.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • mculik5
    mculik5 Member Posts: 30
    Pipe Plugs

    Thanks for the advice about the tape, Bob. I'll look for some better/thicker stuff.

    Nicholas was right. The bungs on one end were tapped and had pipe plugs in them. Not sure if this is the right tool, but I used a hex wrench to get them out.

    However, in the process of prepping threads for plugs, etc., I discovered that my radiators were made in China. I was told Governale radiators are American made, and ordered them specifically for that reason. The radiators do say Governale on them, so not sure what's going on, but these will be going back.

    In your opinions, who makes the best freestanding cast iron radiator?
  • Steve_175
    Steve_175 Member Posts: 238
    Teflon tape

    I have never bothered with tape or dope on radiator vents. Never had a problem. Your millage may vary.
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